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Flashcards in anaesthetics Deck (64):
1

what category of medicine is a topical anaesthetic

POM (prescription only medicine)

so only healthcare professionals have access to them

2

topical anaesthetics are drugs that ____________ block ________________ in ____________ nerves

topical anaesthetics are drugs that reversibly block transmission in sensory nerves

3

list 5 indications for use of a topical anaesthetic

- contact tonometry
- contact lens fitting
- foreign body removal
- gonioscopy
- lacrimal procedures

4

what indication will you never use a topical anaesthetic for

the relief of symptoms

5

what type of contact lens fitting will you use a topical anaesthetic

if your going to make an impression of the eye e.g. for scleral lenses

6

what does topical anaesthetics delay

corneal epithelial cell healing, so it is not good for a patient with corneal abrasions

7

list 3 advantages of topical anaesthetics

- allows certain procedures to be conducted
- makes the patient more comfortable
- makes procedures easier for the practitioner

8

list 4 disadvantages of topical anaesthetics

- stings (due to pH)
- delays healing
- eye is more susceptible to damage (due to delayed healing, it is more compromised)
- repeated installations

9

the most mode action of topical anaesthetic

- _________ information passes along _______ _______ __________ _________ (action potentials)
- nerve has __________ charge at _______
- _______ ________ is generated in _______ of _________ ions into the ________ and this results in a _________ charge (depolarisation)
- efflux of __________ ions returns the nerve to _________ potential causing _______________
- the action potential passes along the nerve along with _____________ ___________ and depolarisations of ________ areas
- topical anaesthetics __________ block nerve conduction
- they block ___________ channels therefore action potentials ______ be generated

- sensory information passes along nerve fibres electrical impulses (action potentials)
- nerve has negative charge at rest
- action potential is generated in influx of sodium ions into the nerve and this results in a positive charge (depolarisation)
- efflux of potassium ions returns the nerve to resting potential causing repolarisation
- the action potential passes along the nerve along with successive depolarisations and depolarisations of adjacent areas
- topical anaesthetics reversibly block nerve conduction
- they block sodium channels therefore action potential can't be generated

10

which topical anaesthetic stings the most

amethocaine (tetracaine)

11

what is the onset and duration of amethocaine

onset 1 min
duration 20 min

12

what is the onset and duration of benoxinate

onset 1 minute
duration 15 minutes

13

what is the onset and duration of proxymetacaine

onset 1 minute
duration 15 minutes

14

what is the onset and duration of lignocaine

onset 1 minute
duration 30 minutes

15

what is another name for amethocaine

tetracaine

16

what is another name for benoxinate

oxybuprocaine

17

what is another name for proxymetacaine

proparacaine

18

what is another name for lignocaine

lidocaine

19

which topical anaesthetic has the longest duration

lignocaine

20

what are the 2 types of possible chemical structures of topical anaesthetics

- ester link
or
- amide link

21

which chemical structure of topical anaesthetic is more linked to allergic reactions

ester link

22

what is the ester link chemical structure hydrolysed by

cholinesterase

23

what is the amide link resistant to

hydrolysation

24

which chemical structure has a longer duration

amide link

25

list the 3 ester link topical anaesthetics

- oxybuprocaine
- tatracaine
- proparacaine

26

what is the amide link topical anaesthetic

lignocaine

27

what portions/parts do all of the topical anaesthetics have

lipophilic (insoluble) and hydrophilic (soluble) parts that are linked together either by an ester link or an amide link

28

which chemical strict of topical anaesthetic is broken down more easily

ester linkage

29

which topical anaesthetic is the most potent and provides the deepest anaesthesia and what does this make it good for

tertacaine (amethocaine)

makes it good for foreign body removal

30

sensitivity of tetracaine/amethocaine is _________ and occurs after ____________ _________

sensitivity of tetracaine/amethocaine is rare and occurs after repeated doses

31

what is tetracaine/amethocaine associated with

punctate staining

32

list the 4 contraindications/cautions of tetracaine/amethocaine

- sulphonamides
- premature babies
- known allergy
- pregnancy/lactation

33

what form of packaging and what doses is tetracaine/amehocaine available in and what are the storage conditions

- 0.5% and 1.0%
- minims
- protect from light (a cupboard stops it from destabilising)

34

what may happen if tetracaine/amethocaine is not protected from light

it will be hydrolysed by the light, causing it to destabilise

35

how can tetracaine/amethocaine damage the cornea

if the solution dose is over 1% concentration

36

what is it possible to do after just one drop of tetracaine/amethocaine

removal or foreign body

37

which topical anaesthetic is the most widely used by optometrists in the UK

oxybuprocaine/benoxinate

38

how likely are sensitivity reactions with oxybuprocaine/benoxinate

rare

39

what does oxybuprocaine/benoxinate have less of that tetracaine/amethocaine

less stinging, irritation

40

what special property does oxybuprocaine/benoxinate have and how can this also be a disadvantage

bactericidal properties

but when want to take a swab of the eye to test for bacteria it produces false results as it has killed some of it off

41

list the 4 contraindications/cautions of oxybuprocaine/benoxinate

- known allergy
- if other eyedrops containing chlorhexidine acetate as a preservative are being used
- pregnancy/lactation
- premature babies

42

what form of packaging and dose is oxybuprocaine/benoxinate available in and what is the storage conditions

- 0.4%
- minims
- store below 25 degrees celsius and protect from light

43

how can oxybuprocaine/benoxinate be used in ophthalmology

- three drops are instilled over a five minute interval which allows foreign body to be removed
- corneal sensation recovers after one hour

44

which topical anaesthetic stings the least

proxymetacaine/proparacaine

45

proxymetacaine/proparacaine causes the minimal __________ ___________ __________, ideal for ___________

proxymetacaine/proparacaine causes the minimal punctate corneal staining, ideal for tonometry

46

why is proxymetacaine/proparacaine used in hospitals more and what is it useful for

because it has the least antibacterial properties, useful when taking conjunctival swabs

47

list the 5 contraindications/cautions with proxymetacaine/proparacaine

- known allergy
- overactive thyroid
- heart disease
- premature babies
- pregnancy/lactation

48

how common is sensitivity with proxymetacaine/proparacaine

rare

49

what form of packaging and dose is proxymetacaine/proparacaine available in and what are the storage conditions

- 0.5%
- minims
- store between 2-8 degrees celsius - has to be kept in a refrigerator

50

what type of surgery can proxymetacaine/proparacaine be used in and how is it used in this condition

cataract extraction
1 drop every 5 - 10 minutes
5 - 7 drops in total

51

which other topical anaesthetic does lidocaine/lignocaine sting less that

tetracaine/amethocaine

52

when is lidocaine/lignocaine used

when a patient is sensitive to the ester link

53

what are the contraindications/cautions with lidocaine/lignocaine

- pregnancy/lactation
- premature babies

54

why is lidocaine/lignocaine good for goldmann tonometry

because it comes combined with fluorescein

55

what form of packaging and dose does lidocaine/lignocaine come in and what are the storage conditions

- 4% minims combined with 0.25% flourescein
- minims
- store below 25 degrees celsius and protect from light

56

what dosage of fluorescein does lidocaine/lignocaine come with

0.25%

57

list 6 possible side effects that can occur with any topical anaesthetic from least to most worse

- transient stinging
- transient blurring
- conjunctival hyperaemia
- mild superficial epithelial damage, especially with stronger drops such as tetracaine which represents local toxicity
- punctate keratitis
- hypersensitivity reactions (less likely with lidocaine), range from mild transient blepharoconjunctivitis to diffuse necrotising epithelial keratitis

58

what is the incidence of necrotising keratitis incidence with ester drugs

1/1000

59

repeated use can lead to __________ ____________ can lead to _______________ _______________

repeated use can lead to epithelial toxicity can lead to serious keratopathy

60

what 4 things can serious keratopathy lead to

- epithelial loss
- stromal oedema
- corneal infiltrates
- anterior chamber reaction

61

what must you instruct to your patient in regards to topical anaesthetics

not to rub the eyes
cannot leave practice until anaesthetic had worn off

62

what is increased by instillation of topical anaesthetic

permeability of epithelium cells thus enhances effect of other drugs e.g. when using in combination with cyclopentolate in dark eyes

63

what is reduced by topical anaesthetics

healing of epithelial cells

64

who is topical anaesthetics open to abuse by

health care practitioners